balance_dir..._ratelimited(9)

💅 balance_dir..._ratelimited — like, the whole vibe ✨

okay so real talk, bestie: this is a page from the Kernel API Manual (section 9, the kernel-API girlies 🎀), and it's about balance_dirty_pages_ratelimited. yes the header truncates the name, no we're not gonna be weird about it, that's just how the man page renders it. periodt. 🦋

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🌸 NAME 🌸

balance_dirty_pages_ratelimited — balance dirty memory state. that's it. that's the whole name section. slay. 💖

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⭐ SYNOPSIS ⭐

void balance_dirty_pages_ratelimited (struct address_space *mapping );

like, it returns void, so don't go looking for a return value, there isn't one, it's giving "i do things, i don't report back" 😭

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🎀 ARGUMENTS 🎀

• mapping — the address_space that was dirtied. yeah, that one. the one you just made messy 🙈

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕: processes that are dirtying memory should call in here once for each page which was newly dirtied. literally once per page, don't be skipping, don't be batch-calling it out of nowhere, iykyk.

the function will periodically check the system's dirty state and will initiate writeback if needed. she checks in on the vibes and, if the vibes are off, she starts the writeback. main character energy honestly 👑

and here's the part where it gets serious — once we're over the dirty memory limit, we decrease the ratelimiting by a lot, to prevent individual processes from overshooting the limit by (ratelimit_pages) each. like, by a lot lot. the whole point is that no single process gets to just bulldoze past the limit by its own ratelimit_pages and ruin it for everyone 💀

ngl this is one of those "call it correctly or the memory balancing gets weird" situations, so, you know. call it once per newly dirtied page. fr fr. 🫶

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🌈 SEE ALSO 🌈

all the sisters, cousins and adjacent girlies, and yes you WILL be reading them:

• Kernel file ./mm/page-writeback.c
• node_dirtyable_memory(9)
• global_dirtyable_memory(9)
• domain_dirty_limits(9)
• global_dirty_limits(9)
• node_dirty_limit(9)
• node_dirty_ok(9)
• __wb_calc_thresh(9)
• balance_dirty_pages_ratelimited_flags(9)
• wb_over_bg_thresh(9)
• tag_pages_for_writeback(9)
• writeback_iter(9)
• filemap_dirty_folio(9)
• folio_redirty_for_writepage(9)
• folio_mark_dirty(9)
• folio_wait_writeback(9)
• folio_wait_writeback_killable(9)
• folio_wait_stable(9)

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and that's the page, bestie 🧚💜 this little cutie lives in the ./mm source tree, dated October 2026, and yes the footer is literally just balance_dir..._ratelimited(9) again because man pages love a good repetition moment. mwah 💋✨